276 Strawherry-Growing 



young aphids from the leaves and crowns to the roots. The ants 

 feed on the honey dew that is secreted by the aphids. They carry 

 the aphids to new plants when infested plants die, thus spreading 

 the pest. When the food supply becomes short, winged female 

 forms appear which fly to neighboring fields and establish new colo- 

 nies. In late autumn true males and females appear, pair, and eggs 

 are laid to continue the species over winter. 



Parasitic enemies are abundant, but do not keep the aphids in 

 check. Secure clean plants and set them on clean land. Avoid corn 

 or melon fields which have been infested with the corn or melon 

 aphis ; such fields contain numerous ants which aid in spreading the 

 strawberry root-louse. If there is any doubt about the plants being 

 clean, disinfect them before they are set. This is performed suc- 

 cessfully only when all the eggs have hatched ; neither fumigation 

 nor dipping can kill the eggs mthout injuring the plant. If disin- 

 fection is delayed until the eggs have hatched, however, this makes 

 the planting season late. Dip the plants for a few minutes in a to- 

 bacco decoction or in dilute nicotine sulfate, one part to 1000; or 

 fumigate w^th hydrocyanic acid gas, using one ounce per cubic foot 

 of space for ten minutes. Plow old beds as soon as the crop has been 

 harvested. In the North, if the field is burned over in early spring, 

 this destroys the eggs ; in the South, the aphids winter on the roots 

 and burning is not effective. 



Crown borer (Tyloderema fragarice). 



In the upper Mississippi Valley, strawberry plants are attacked 

 by a thick grub, one-quarter of an inch long, white with a brown head, 

 which burrows in the crown. In early spring, a chestnut brown 

 snout-beetle, one-sixth of an inch long, deposits eggs in the plant 

 near the surface of the ground, selecting the older plants. The 

 borer reaches maturity in July and August and is transformed 

 into a beetle in the cavity it has made. There is one generation 

 a year. 



The beetles cannot fly, so the insect spreads very slowly. A short 

 rotation prevents it from becoming estabhshed. If plants for new 

 settings are dug very early in the spring, before the eggs are laid, 

 there is no danger of spreading the pest. Plow under or burn all 

 the plants in a field that is badly infested as soon as possible after 

 the fruit is harvested. 



